There is a need for interventions for older teens (16-17) who are engaging in alcohol and/or sexual risk behaviors. Older teens become more autonomous and the role of the parent becomes more difficult as they balance providing guidance while relinquishing control. Parents struggle with the right mix of monitoring and guidance. If a family-based approach to address these teen behaviors is effective, this new program could potentially provide a low cost and important strategy for improving the health and safety of older teens. This study will develop a web-based intervention for 16-17 year old youth and their parents. The aims are as follows: Specific Aim 1: To adapt two parent-based prevention strategies (Family Matters and Parent Handbook) to provide a family-based approach for addressing older teen alcohol related risk behaviors and sexual risk behaviors and sex in combination with alcohol use (hereafter called alcohol and/or sexual risk behaviors) using the web as the program delivery mode. Specific Aim 2: To test whether exposure to the program leads to expected changes in targeted teen beliefs and behaviors, including reductions in alcohol and/or sexual risk behaviors. Specific Aim 3: To examine whether program effects on teen alcohol and/or sexual risk behaviors are mediated through changes in intermediate program targeted beliefs (parents and teen) and behaviors (parent-teen--communication). Program fidelity and process measures may also mediate these outcomes. Phase I integrate and adapt the two parent-based approaches and creates a web-based interactive delivery of materials. Expert panels, focus groups, and usability assessments will inform the process. Phase II is an RCT with 500 families with the web-based intervention. Surveys will be conducted at baseline, and for three follow-up periods (6, 12, & 18 months). Analyses will examine teen outcomes related to alcohol and/or sexual risk behaviors. Changes in mediators directly impacted by the program for both teens and parents will be examined. Process and fidelity information will be collected and assessed. PUBLIC HEALTH RELEVANCE: Prevalence of lifetime alcohol use increases as teens get older, with national estimates indicating by 12th grade 82.8% of teens have consumed alcohol, 62.3% have engaged in sex. Parents are an important part of the societal infrastructure to provide teens with guidance on these behaviors. Developing an intervention delivered over the web provides a feasible and easily disseminated approach.